Description of Problem:

Attach dialog defaults to /home instead of remembering user's selection in
a previous use of 'attach' -- or allowing user to control default attach
directory via a configuration setting.

Steps to reproduce the problem:
1. Compose a message, click "Attach", navigate to a sub-directory
2. Attach document, send message, exit Evolution
3. Repeat step 1

Actual Results:

Clicking "attach" returns to /home

Expected Results:

Should return to previously selected directory as per bug#247547, which
described similar behavior on the save side of things.

How often does this happen? 

Everytime

Additional Information: